Automatic shut-off device.



I A. LEVEDAHL. AUTOMATIC SHUT-OFF DEVICE.

APPLICATION FILED MAYZO, 1914 1,1 33,483. Patented Mar. 30, 1915.

2 SHEETSSHEET 1.

Q E Q f t A Wlrfifis'ear N .TnvenTcTr W W N N Axel Levedahl MQ/W f aim/5.

IHE NORRIS F'EIFRS C0,. PHOTO-Luna, WASHING "IN. 0. (I.

A. LEVEDAHL.

AUTOMATIC SHUT-OFF DEVICE.

APPLIOATION FILED muzo, i914.

Patented Mar. 30, 1915.

2 SHEETS-SHEET 2.

THE NORRIS PETERS 60.. PHQTC-LITHu, WASHING TON D. L.

AXEL LEVEDAHL, 0F AURORA, ILLINOIS, ASSIGNOB TO AURORA AUTOMATIC MACHINERY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF DELAIK ARE.

AUTOMATIC SHUT-OFF DEVICE.

Specification of Letters Patent.

Patented Mar. 39, 1915.

. Application filed May 20, 1914. Serial No. 839,677.

T 0 all whom. it may concern:

Be it known that I, AxEL LEVEDAI-IL, a citizen of the United States, and a resident of Aurora, in the county of Kane and State of Illinois, have invented certain new and useful Improvements in Automatic Shut-Off Devices; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, and to the letters of trial plants for the purpose of heating, tempering or hardening metals or materials, in applying and hardening enamels and in like operations. These furnaces or ovens are ordinarily heated by means of burners located within the furnace or oven to which a mixture of gas and air is conducted and ignited, the gas and air being mixed prior to reach ing the burners within the furnace or oven.

Serious accidents have frequently occurred in factories Where ordinary gas ovens and furnaces are in use, due to the interruption or irregularity of the supply of gas or air to the oven and the absence of means for shutting off the supply or means for informing the. operator of the conditions. For instance, should the flow of gas be interrupted for some reason beyond the control of the immediate regulating valves, even for a very short time, the burners within the oven would be extinguished without the fact being brought to the immediate notice of the attendant, and, upon the flow of gas being resumed, the gas would escape from the burners into the oven and the room, thus filling the surrounding space with an explosive mixture which from one cause or another might be accidentally ignited and a violent explosion occur. So also, if the air Were accidentally cut off, the gas would continue to burn, but with the well-known yellow flame that accompanies the ignition of gas unmixed with air, and with the production of carbon or soot which would be deposited upon the surfaces of the articles being treated. The result of this deposit would be injurious, particularly where the operation was that of hardening or drying an application of enamel.

The principal purpose of my invention is to provide an automatically operated valve or valve controlling means adapted to instantly shut off the flow of the gas to the oven whenever the supplv of either the gas or air becomes interrupted or discontinued for any reason, and to permit the operation of gas operated furnaces or ovens during long periods without the constant attendance of an operator.

My invention therefore consists in the matters hereinafter described, more particularly pointed out in the appended claims, and fully illustrated in the accompanying drawings, in which,

Figure 1 is a view in side elevation, showing the arrangement of an oven or furnace and my improved shut-ofi' device; Fig. 2 is a view in end elevation of the apparatus shown in Fig. 1; Fig. 3 is an enlarged detail view, showing the shut-off device with parts thereof in section; and Fig. 4 is an enlarged detail view of the shutoff valve.

Referring to the drawings: A heating or enameling oven or furnace 10 of the usual construction is shown (Figs. 1 and 2) as mounted upon a platform or table 11.

Within the oven are a plurality of burners which are supplied with a combustible mixture, preferably of intermixed illuminating gas and air, by means of the fuel supply pipe 12 which enters at the bottom of the oven. The mixture supply pipe 12 communicates with two branch pipes 13 and 14, the pipe13 being the gas supply pipe and the pipe 14 the air supply pipe. These pipes are connected, so that the mixture of the gas and air takes place, by preference, substantially adjacent to the upper extremity 15 (Fig. 2) of the gas supply pipe 13. The lower end of the air supply pipe 14 communicates with the interior of a collapsible bellows 16, with which said pipe is connected, by means of a flexible pipe 17. The pipe 14 communicates With-a horizontal pipe 18, which communicates with a source of air supply in the form of a. compressor or blower or other means for supplying and delivering air under pressure. The air supply pipe 14% is also provided with a valve 19, preferably adjacent to its delivery end, for the purpose of regulating the flow of air through the pipe and The receiving end of the pipe 13 communiprovided with one or more pins or lugs 2 cates with a pipe 21 which in turn communicates with a suitable source of gas supply, adapted to provide and maintain a supply of gas under suitable pressure. The pipe 21 is connected with a gasometer 23, preferably by means of a branch or connecting pipe 22. Referring now in detail to the construc tion of the means for automatically closing the gas regulating valve '20, the same is preferably of the globe type, ordinar ly used for this purpose, and is provided with a stem 9A and hand-wheel 25 (Figs. 3 and 4), adapted to be rotated in opposite d rections in the operation of opening and closing the valve. Rigidly secured to the rotative valve stem 24:, is a pulley wheel 26, shown herein as mounted immediately adjacent to the hand-wheel 25. The pulley is l i which are shown spaced apart and concentrically arranged adjacent to the periphery of the pulley wheel. The face of the pulley is preferably groovedand carries a flexible metal band or ribbon 28 surrounding the peripheral surface of the pulley and secured thereto at one end. The free end of the flexible band extends downward from the pulley at one side thereof into a cylindric casing or dash pot 29,- mounted in vertical position beneath the pulley and secured upon the floor or upon a suitable base. .To the free'end of said flexible band 28 is suspended a piston 30, which is sufliciently heavy to operate the pulley and thereby the valve when the piston or pulley is released. The piston is adapted to fit within the dash pot and to be moved upwardly and downwardly therein. The piston is preferably provided with an encircling packing ring 31, adapted to permit free movement of the piston with lubrication, and is also provided with a vertical passage 30 therethrough ofsuitable size to permit the escape of air from the space below the piston, so as to allow the latter to descend to close the valve.

Adjacent to the dash pot 29 is a pawl 32, shown in Fig. 3. The pawl is in the form of a flexible metallic rod or bar, provided at its lower end with an angular bent portion 32 securely fastened to the floor or other suitable support. In this manner a (JEHSQS.

certain degree of flexibility-is given the pawl, so that it may be moved or oscillated a bout its lower extremity. The upper end of the pawl is bent transversely to provide a tooth or projection 33 adapted to engage a pin 27 on the pulley 26, adjacent to the point where the flexible band leaves the pulley. T he engagement of the pawl with a pin on the pulley 26 acts to prevent the rotation of the pulley. and the valve by the action of the piston on said pulley. By reason of the flexible nature of the pawl, it is also adapted to be disengaged from the pins of the pulley, and to thus permit the weight to fall by gravity and thus effect the closure of the gas supply valve.

If ow referring in detail to the devices which I employ to actuate the pawl for the purpose of disengaging the same from the pins 27' of the pulley, such devices are con-- structed and arranged as follows: Adjacent to the pawl 32 is located the bellows 16, before mentioned as connected with the air supply pipe 1-1 by means of the branch pipe 17. The bellows may be of any desired, ordinary or well known form, comprising two relatively movable members 34: and 35 which are flexibly connected by means of flexible material adapted to form inclosing walls 36, thereby forming an expansible, collapsible chamber adapted to contain a volume of air, the pressure of the air within said chamber acting to expand the bellows. In this instance one of the members is fixed in horizontal position upona base 37. The upper or movable member 34 is hinged along one margin and is adapted to be moved upwardly and downwardly as the pressure of the air entering the bellows is increased and decreased. The member 34: supports upon its surface a weight 38 for the purpose of assuring a rapid and complete collapsing of the bellows in the in stance that the supply of air to the bellows of the H The movable member 3% ,W hen the bellows are collapsed, however,

theidownward movement of the member 3& results in a tightening of the cord suflicient to produce a pull on the pawl of sufficient force to effect a disengagement of the pawl with respect to the pins 27 of the pulley 26 and the immediate closure of the valve, in.

the manner before set forth. I alsoproride a similarly operated means acting to,

release the pawl which is controlled by the flow of gas in the gas supply pipe. This device is the gasometer 23, shown herein as mounted above the floor upon a platform 40. Said gasometer comprises a rectangular shaped vessel 41 having a bottom wall and outer and inner vertical walls 42 and 43, the inner wall being spaced inwardly from the outer wall, thereby forming an annular space surrounding and separated from the space formed within the inner wall. Extending over the vessel 41 is a similarly shaped inverted vessel or cover 44, the marginal walls of which are adapted to extend downwardly into the space between the outer and inner walls of the vessel 41,

said space being partially filled with water to provide a water-sealed space within the vessel; One margin of the inverted cover is hinged to the bottom wall of the vessel 41 by means of hinges 45, so that said cover is free to be swung upwardly and downwardly about said margin, as the volume of gas contained in the inner expansible and collapsible chamber of the gasometer is increased or decreased. The pipe 22, hereinbefore mentioned as communicating with the gas supply pipe 21, projects upwardly through the bottom of the vessel 41 and into the inner chamber of the gasometer. (See Fig. 3.) The vessel'44 is provided upon its upper surface, adjacent to its hinged margin, with a bracket or arm 46, to which is fastened one end of a cord, chain or connecting member 47, said cord being secured at the other end to the pawl. 32. This cord serves to operate the pawl 32 in a manner similar to the operation of the cord 39, hereinbefore described in connection with the bellows 16, and hence need not be further described. A weight 48 is mounted 011 the cover 44, at its end opposite the hinged margin, for the purpose of aiding the downward movement of sald cover 44 and thereby releasing the pawl 32 from engagement with the valve operating pulley 26 when the gas pressure in the gasometer is reduced so as to permit the down ward movement of the part 44.

Referring now to the operation of the automatic shut-ofi device, let it be first assumed that the supply of air and gas isconstant and that the oven is in operation. Under these circumstances the valve 20 of the gas supply pipe is inopen position, the pulley 26 being engaged by the pawl 32, so as to prevent the rotation of the same by means of the piston 30. Under these conditions of operation, the gas, in passing through the supply pipe 21, enters the gasometer 23 through the pipe 22 from the supply pipe 21. The normal pressure of the gas thus entering the gasometer acts to maintain the hinged cover 44 in its raised position. In this position of the cover 44 of the gasometer, the cord 47, extending from the bracket 46 of the gasometer to the upper portion of the pawl, is sufliciently loose to permit the engagement of the pawl 32 with a pin 27 of the pulley 26; In these condi tions also the air enters the bellows 16 through the branch pipe 17 and maintains a quantity of air therein under a pressure equal to the pressure of the air supply, said pressure being suilicient to expand the bellows and tomaintain the same in expanded condition. When the bellows are thus expanded, the cord 39 connecting the movable member 34 of the bellows with the pawl 32 is also sufliciently loose or lax so that no force is exerted thereby upon said pawl tending to disengage the same from a pin 27 of the pulley 26.

From the foregoing description of the bellows and gasometer, and the manner in which they communicate with the air and gas supply pipe, respectively, it is obvious that so long as the air and gas continue to flow uniformly and at a constant pressure the bellows and gasometer will remain expanded and the cords connecting each with the pawl will not be stretched or expanded so as to release the pawl 32. The gas valve 20 will therefore remain open. However, should either the gas or air supply be interrupted or shut off for any length of time however short, due to an accident to the source of supply or other cause, the pressure within the bellows or the gasometer would be immediately reduced. Assuming first that the gas supply should for any reason he cut oil", the reduction of the pressure Within the gasometer would result in the lowering of the cover 44 about its hinged margin, this movement being accelerated by the weight 48 mounted on said cover. The lowering of the cover to the position shown in dotted lines in Fig. 3, would result in the swinging movement of the bracket 46 in a direction away from the pawl 32 and would act to exert a pull upon the cord 47 attached thereto, which pull is transmitted to the pawl 32, moving the same to the dotted line position showirin Fig. 3, thus effecting the disengagement of the pawl from the pin 27 of the pulley with which it is normally engaged. The pulley 26 would thus be free to be rotated under the weight of the piston 30 which would immediately drop to the lower end of the dash pot 29, as shown in dotted lines in Fig. 3. The rotation of the pulley, due to the dropping of the piston, closes the gas valve 20 and prevents further admission of gas to the oven until the gas supply is again resumed and the valve again opened by revolving te pulley to raise the piston and the engagement of the pulley and the pawl 32. The air supply is not efiected by the automatic shutting 0E of the gas, but of course this would not be necessary in view of the harmless nature of the air. Now, assuming that the air supply be interrupted and the flow of gas continued in its normal flow, it is evident that the air pressure with in'the bellows 16 will immediately decrease and the bellows collapse to the dotted line position shown in Fig. 3, the hinged member 34: of the bellows being lowered to its horizontal or collapsed position. As the bellows collapse, the cord 29 will be tightened and exert a pull upon the pawl 32 acting to disengage the same from the pulley 26, thus effecting the closure of the gas valve 20 in precisely the same manner as before described in connection with the operation of the gasometer.

It is very desirable to shut off the oven when the air supply fails, in order to avoid the burning of the pure gas which, as before stated, burns with a yellow flame producing soot which would be deposited upon the. surface of the articles being treated within the furnace to their injury. By using a bellows for the purpose of actuating the pawl when an interruption of the air supply occurs, the advantage is apparent. The large capacity of the bellows permits a considerable quantity of air to be retained therein. This air will be forced through the supply pipe during the collapsing of the,

bellows after the regular supply of air has ceased, and the air will thus be mixed with the gas remaining in the pipes after the gas valve has been closed, so that the entire quantity of gas beyond the'closed gas valve will be forced into the oven and burned with air. In this manner the gas thus remaining in the pipe after the gas supply is shut off is prevented from burning in the oven with the yellow flame due to the absence of sufficient air to produce the proper combustible mixture. Furthermore, the air, furnished by the bellows subsequent to the shutting off of the gas and air supply, prevents a partial vacuum being formed in the mixture supply pipe 12 and the burners within the oven, which would result in backfiring or an explosion in said pipe and burners.

My invention, therefore, provides a simple and dependable means for controlling gas operated ovens or furnaces by automatically and safely discontinuing the operation of said ovens and furnaces and shutting off the fuel or gas supply until the defect in or interruption of the gas or air supply is brought to the notice of the operator and the proper conditions are established.

It is to be understood that a device of the character described may be applied to a vseriesof ovens or furnaces where a'nuinber are operated from a common source of gas and air supply, in which case the device would automatically shut off the gas supply to all or any desired number of ovens and furnaces with which the same is operatively connected.

The device embodying the features of my inventioi may be variously modified Without departing from the spirit of my invention and for that reason I do not wish to be so far as specifically set forth in the claims.

1 claim as my invention: 1. In an automatic shut-off device, the

combination of two fluid supply pipes united to form a mixture supply, one of said pipes being a gas supply pipe, a valve for cutting off the flow of gas, an automatically operating member attached to said valve adapted to close the valve, retaining means normally engaging said automatically operating member to prevent the clo sure of said valve, and independent means controlled by the pressure of the fluid in either of said supply pipes, for automatically releasing said retaining means to per mit the closure of said valve when the pressure in either supply pipe is decreased.

' 2. In an automatic shut ofi device, the combination of a gas and an air supply pipe united to form a mixture supply, a valve in said gas supply pipe, gravityactuated means adapted to close said valve, retaining means acting to prevent the'action of the gravity-actuated means upon said valve, and independent means controlled by the pressure in each of said supply pipes, for

releasing said retaining means to permit the closure of the valve by said gravityactuated means when the pressure in either supply pipe is decreased.

3. In an automatic shut-off device, the

combination ofgas and air supply pipes united to form a mixture supply, an automatically closing valve in said gas supply pipe, and a vessel communicating with each of said gas and air supply pipes, each vessel being provided with a movable memberoperatively connected with said valve and adapted tobe actuated by the variation of pressure in said supply pipes, to effect the closure of said valve when the pressure in either of said supply pipes s-decreased.

a. In an automatic shut-oft device, the combination of gas and vairsupply pipes united to provide a mixture supply, avalve in said gas supply pipe provided with means for automatically closing the same, retaining means normally acting to prevent the closure of said valve,-and independent means operatively connected with said re taining meansand actuated by the variation in pressure in each supply pipe to efiect the closure of said valve when the pressure in either supply pipe is decreased, said means associated with the air supply pipe, acting to provide a quantity of air to said mixture supply after said valve has been closed by said last mentioned means.

5. In an automatic shut-off device, the combination of a gas and air supply pipe united to form a mixture supply, an auto matically controlled valve in said gas supply pipe, retaining means acting to normally maintain said valve in open position, and means controlled by the variation of pressure in said air supply pipe and operatively connected with said retaining means, to effect the closure of said valve when the pressure in said air supply pipe is decreased, and adapted to supply a quantity of air under normal pressure to said mixture supply after said valve has been closed.

6, In an automatic shut-ofi' device, the combination of gas and air supply pipes united to form a mixture supply, a valve in said gas supply pipe, means for automatically closing said valve, means for normally retaining said valve in open position, means controlled by the variation of pressure in said gas supply pipe, and operatively connected with said retaining means, for effecting the closure of said valve when the pressure in said gas supply pipe is decreased, and a bellows communicating with said air supply pipe and having its movable member operatively connected with said retaining means, said bellows acting to effect the closure of said valve when the pressure in said air supply pipe is decreased and to supply a quantity of air under normal pressure to said mixture supply after said valve has been closed by said bellows.

In an automatic shut-off device, the combination of a gas and an air supply pipe united to form a mixture supply, a valve in said gas supply pipe provided with a rotative valve stem, a wheel operatively connected with said valve stem, a weighted member suspended from said wheel, a retaining pawl adapted to engage said wheel to prevent the rotation thereof by said weighted member, a vessel communicating with each of said gas and air supply pipes, each of said vessels being provided with a movable member adapted to be actuated by the fluid pressure within the vessel, and operatively connected with said pawl to release the same from said'wheel, when the pressure in either the gas or air supply pipe is decreased.

8. In an automatic shut-off device, the combination with gas and air supply pipes, of a valve in said gas supply pipe provided with a valve stem to close said valve, an automatically operating member operatively connected with said valve stem, a movable pawl adapted to normally engage said automatically operating member to prevent the operation thereof, a gasometer communicating with said gas supply pipe, a bellows Copies of this patent may be obtained for five cents each, by addressing the communicating with said air supply pipe, and means connecting the movable portions of said gasometer and bellows with said movable pawl.

9. In an automatic shut-off device, the combination with a gas supply pipe, of a valve in said pipe provided with a rotatable valve stem for closing said valve, a pulley wheel mounted on said valve stem and provided with a projection, a dash pot, a plunger suspended from said pulley wheel and movable in said dash pot, a movable pawl adapted to engage said projection of the pulley wheel to prevent the rotation thereof, and means actuated by the variation of pressure in said gas supply pipe and operatively connected with said pawl, for releasing said pawl when the pressure in said pipe is decreased.

10. In an automatic shutoff device, the combination with a gas supply pipe, of a valve in said pipe provided with a rotatable valve stem, a pulley wheel mounted on said valve stem and provided with a plurality of. concentrically arranged pins adjacent to the periphery thereof, a dash pot, a plunger suspended from said pulley wheel and movable in said dash pot, a movable pawl adapted to engage one of said pins of the pulley wheel to prevent the rotation thereof, a gasometer communicating with said fluid supply pipe, and a flexible member connecting said pawl and the movable member of said gasometer.

11. In an automatic shut-olf device, the combination with gas and air supply pipes, of a valve in said gas supply pipe provided with a rotatable valve stem, a pulley wheel mounted on said valve stem, a dash pot, a plunger in said dash pot connected with said pulley wheel, a movable pawl adapted to engage a projection on said pulley wheel to prevent rotation thereof, a gasometer communicating with said gas supply pipe, a bellows communicating with said air supply pipe, and means connecting the movable members of said gasometer and bellows with said movable pawl.

In testimony, that I claim the foregoing as my invention I aflix my signature in the presence of two witnesses, this 16th day of May A. D. 1914.

AXEL LEVEDAI-IL.

Witnesses:

R. A. NoRLiNe, F. S. RHOADS.

Commissioner of Patents,

Washington, I). G. 

